Re: internal dummy connection (some thoughts on IPv6 support)

[Randolf Richardson <ra...@modperl.pl>]

	In addition to the responses from others, I just wanted to point out 
that the string "::1" is an IPv6 equivilant to "127.0.0.1" in IPv4, 
both of which are normally associated with the "localhost" hostname.

	IPv6 has been in production for many years now, and due to the 
shortage of available IPv4 addresses it is becoming increasingly 
prevalent throughout the world.  For a real world implementation, one 
good example can be seen in PostgreSQL's documentation:

		https://www.postgresql.org/docs/10/static/datatype-net-types.html

	Perl itself and mod_perl2 both support IPv4 and IPv6 without any 
difficulties in the projects that I work on, so with that in mind...

	If you have any code that arbitrarily supports only IPv4 addresses, 
then you should seriously consider making it a higher priority to add 
support for IPv6.  For example, if you rely on Regular Expressions to 
validate IPv4 addresses specifically, then be aware that any valid 
IPv6 addresses will not register as matches due to the inclusion of 
additional characters that are not used to represent IPv4 addresses.

> I saw many items like these in log,
> 
> ::1 - - [05/Jun/2017:14:29:06 +0800] "OPTIONS * HTTP/1.0" 200 125 "-" 
> "Apache/2.4.7 (Ubuntu) PHP/5.5.9-1ubuntu4.21 mod_apreq2-20090110/2.8.0 
> mod_perl/2.0.8 Perl/v5.18.2 (internal dummy connection)"
> ::1 - - [05/Jun/2017:14:29:07 +0800] "OPTIONS * HTTP/1.0" 200 125 "-" 
> "Apache/2.4.7 (Ubuntu) PHP/5.5.9-1ubuntu4.21 mod_apreq2-20090110/2.8.0 
> mod_perl/2.0.8 Perl/v5.18.2 (internal dummy connection)"
> ::1 - - [05/Jun/2017:14:29:08 +0800] "OPTIONS * HTTP/1.0" 200 125 "-" 
> "Apache/2.4.7 (Ubuntu) PHP/5.5.9-1ubuntu4.21 mod_apreq2-20090110/2.8.0 
> mod_perl/2.0.8 Perl/v5.18.2 (internal dummy connection)"
> ::1 - - [05/Jun/2017:14:29:09 +0800] "OPTIONS * HTTP/1.0" 200 125 "-" 
> "Apache/2.4.7 (Ubuntu) PHP/5.5.9-1ubuntu4.21 mod_apreq2-20090110/2.8.0 
> mod_perl/2.0.8 Perl/v5.18.2 (internal dummy connection)"
> 
> what does it mean? why it exists? thanks.


Randolf Richardson - randolf@inter-corporate.com
Inter-Corporate Computer & Network Services, Inc.
Beautiful British Columbia, Canada
http://www.inter-corporate.com/